The Preparation Of Ceria-Zireonia Solid Solution And Its Application In Diesel Oxidation Catalysts

In this paper, Ceria-Zirconia composite oxide with high thermal stability was prepared by the study of different preparation methods, conditions and elements doping. Then, with Ceria-Zirconia composite oxide as carrier, Pt oxidation catalyst was prepared and showed good catalytic oxidation activity for CO and C3H8. The properties of Ceria-Zirconia composite oxide (Ce0.7Zr0.3O2) including textural-structural property, redox property, oxygen storagerelease capacity, and thermal stability, as well as the catalytic oxidation activity of Pt oxidation catalyst, were investigated by means of N2adsorption/desorption (BET), X-ray Powderdiffraction (XRD), temperature programmed reduction (H2-TPR), oxygen storage capacity complete (OSC) and Self-laboratory catalyst evaluation device etc. The following results were obtained:1. The results showed that compared to other preparation methods, the fresh Ceria-Zirconia solid solution prepared by hydrothermal possessed the largest surface area (106.6m2/g) and mesopore volume (0.224cm3/g), as well as wider mesopore-size distribution and better thermal stability. After aging at1100℃, the Ce0.7Zr0.3O2still possessed higher surface area (35.31m2/g) and mesopore volume (0.1765cm3/g), as well as the highest OSC value (365.7μmolO2/g). Moreover, results from catalyst activity test indicated that Pt oxidation catalyst with optimized oxide Ce0.7Zr0.3O2as carrier had good catalytic oxidation activity for CO and C3H8, which showing relatively lower light-off temperature and complete transition temperature.2. The results showed that the optimized hydrothermal prepared conditions is to precipitate by hydrothermal treatment at150℃for3h with a pH value of9.5. while the optimized oxide exhibited the largest surface area and mesopore volume, as well as wider mesopore-size distribution and better thermal stability. The Pt catalyst supported on fresh and aged Ceria-Zirconia solid solution also showed better oxidation catalytic properties for CO and C3H8.3. The results showed that the number of oxygen vacancy and OSC capacity were improved by the tertiary component doping. Compared to the doping of Al or Al+Si, more homogeneous ternary composite oxides were obtained by the adding of Si to Ceria-Zirconia composite oxides and only cubie phase was observed after aging at1100℃. The structural and textural thermal stabilities of Ceria-Zirconia composite oxides were improved obviously by Si doping. The textural-structural stability and OSC value were improved remarkably when the mass ratio of Si:(Ce+Zr) was1:2. In addition, surface area, mesopore volume and OSC value of the Ce-Zr-Si composite oxides were196.1m2/g,0.3889cm3/g and613.8μmolO2/g, respectively, demonstrating that the Ce-Zr-Si composite oxides existed the largest specific surface area and mesopore volume after aging at1100℃for5h. Furthermore, the Pt catalyst supported on the aged carrier also had the Lowest light-off temperature and complete transition temperature for CO and C3H8.